Roofing products, photovoltaic roofing elements and systems using them

A roofing product having a top surface and one or more overpressed zones, the roofing product comprising:

• a bituminous roofing substrate having a top surface;
• and
• a plurality of roofing granules, each disposed at the top surface of the bituminous roofing substrate in an overpressed zone of the roofing product, each roofing granule embedded in and extending from the top surface of the roofing product, wherein the roofing granules are embedded so that
• in each over-pressed zone the average granule embed volume fraction is at least 0.7, the granule embed volume fraction for each roofing granule being the fraction of the roofing granule that is disposed beneath the level of the top surface of the bituminous roofing substrate, discounting any meniscus formed at the roofing granule;
• or
• in each over-pressed zone, the average distance between the top of the roofing granules and the top surface of the bituminous roofing substrate is 0.5 mm or less, discounting any meniscus formed at each roofing granule.